Vinylcyclohexanethiol modified polymers



VINYLCYCLOHEXANETHIOL MODIFIED POLYMERS Fredrick M. Smith, Rosamond, Calif., and James E.

Pritchard, Bartlesville, Okla, assignors to Phillips Petroleum Company, a corporation of Delaware No Drawing. Original application Sept. 8, 1952, Ser- No. 308,715, now Patent No. 2,842,526, dated July 8, 1958. Divided and this application July 30, 1957, Ser. No. 675,021

11 Claims. (Cl. 260-7 9) This invention relates to polymers modified by a vinylcyclohexanethiol. In one aspect, the invention relates to vinylcyclohexanethiol-containing polymers. In another aspect, the invention relates to a method for the preparation of a polymer prepared using a vinylcyclohexanethiol as a comonomer. lates to the production of a sulfur-containing benzeneinsoluble synthetic rubber. In a still further aspect of the invention, it relates to the treating of a synthetic polymer or copolymer in latex or solution form with a vinylcyclohexanethiol to obtain lower Mooney value rub bers or softer but largely benzene-insoluble polymers and resinous materials insoluble in benzene, e.g., butadiene and styrene are copolymerized in the presence of vinylcyclohexanethiol or polybutadiene in latex, or, say, benzene solution form, is treated with vinylcyclohexanethiol to obtain lower Mooney value rubbers, softer but largely benzene-insoluble polybutadiene and gel-like resinous material insoluble in benzene, respectively.

This application is a divisional application of Serial Number 308,715, filed September 8, 1952, and now U.S. Patent 2,842,526, issued July 8, 1958.

In accordance with the present invention, a vinylcyclohexanethiol, as described in U.S. Patent 2,842,526, can be incorporated into a synthetic rubber by adding it to a recipe from which such a rubber is prepared or to a latex or to a solution to produce a synthetic rubber or resin having desirable properties.

The vinylcyclohexanethiols produced in accordance with this invention are useful as modifiers in the production of synthetic rubber. They are also useful for treating rubber-like polymers to convert said polymers to oilresistant resins.

The synthetic rubber or polymer can be one prepared by polymerization of a recipe containing butadiene alone or together with another monomer, say, styrene. A polymer prepared from butadiene alone, in latex, recipe or solution form, can be contacted with vinylcyclohexanethiol in the presence of oxygen to produce a useful product as herein further described.

An object of this invention is the production of modified synthetic polymers. Another object of the invention is the provision of a method for producing modified synthetic polymers. A further object of the invention is the production of a modified synthetic rubber or rubber-like material which is possessed of a desirably low Mooney value and/or is insoluble in benzene to a substantial extent.

Other aspects, objects, and advantages of the invention are apparent from the study of this application and the appended claims.

Example I Vinylcyclohexanethiol prepared as described and claimed in U.S. Patent 2,842,526 and having a boiling point in the range 98-101 C. 208.4-213.8 F.) at 35 mm. Hg and a refractive index, n of 1.5106 was used as a modifier in a series of runs for the copolymeriza- In a further aspect, the invention re- 1 tion of butadiene with styrene at 50 C. The polymerization recipe was as follows:

Parts by weight Butadiene Styrene 25 Water 180 Sodium soap flakes 5 Vinylcyclohexanethiol Variable Potassium persulfate 0.3

The following results were obtained:

Conver- Mooney Vinylcyclohexauethiol, Wt. Time, siou, Value, Parts by Weight Percent Hours Percent ML4 These data show that increased proportions, in the range 0.1 to 0.6 weight percent of vinylcyclohexanethiol in the recipe result in decreased Mooney values, yielding a desirable rubber product.

Example 11 A sample of 58 Mooney (ML-4) polybutadiene in latex form was treated with vinylcyclohexanethiol, prepared as hereinbefore described, in an amount sufiicient to saturate 1.5 percent of the double bonds (assuming that there is one double bond per 0., unit in the polybutadiene molecule and that one mole of mercaptan reacts with each double bond). The mixture was agitated for 176 hours at 50 C. in the presence of oxygen. The resulting rubbery polymer contained 1.96 percent sulfur, corresponding to saturation of 3.6 percent of the available double bonds. This'product was slightly softer than the original polybutadiene and was composed largely of benzene-insoluble material of utility in products required to contact benzene and like materials.

Example III A benzene solution of 58 Mooney (ML-4) polybutadiene was treated with vinylcyclohexanethiol in an amount sufiicient to saturate 30 percent of the double bonds (assuming that there is one double bond per C unit in the polybutadiene molecule and that one mole of mercaptan reacts with each double bond). After the mixture was agitated at 50 C. for 88 hours, in the presence of oxygen a material was obtained which contained 3.18 percent sulfur, corresponding to saturation of 6.8 percent. The product was a gel-like, resinous material which was insoluble in benzene and exhibited low swelling characteristics after being immersed in benzene for several weeks.

Examples II and III show that a benzene-resistant rubber is obtained by treating polybutadiene with vinylcyclohexanethiol in the presence of oxygen for a time in the range 88 to 17 6 hours. A temperature in the range 20 to C. is suitable.

Variation and modification are possible within the scope of the foregoing disclosure and appended claims to the invention, the essence of-which is that a vinylcyclohexanethiol for example, as prepared by the catalytic reaction of vinylcyclohexene with hydrogen sulfide can Patented Feb. 28, 1961 rubber which iseherr'iicallyknodified by the incorporation therein-f a'small modifying amount of monovinylcyclohexanethiol.

2. A process for preparing synthetic rubber which process comprises subjecting to copolymerizat-ion conditions a mixture comprisingbutadien'e;styrene;water; a

sodiuin' soap, potassium persulfate, and from 0.1 to 0.6

weight percent'of vinylcyclohexanethiol, and-recovering a synthetic rubber material SO'IH'OdUCEdir 3. A- method of preparing a-- benzene-insoluble synthetic rubber Which-cornprises-mixing a" poly'bufacliene with monovinylcyclohexanethiol in an amout sufficient to saturate-from 15- to 30 percentof the double bonds in said polybutacliene; agitating the mixturefora time in the range 88 to 176 hours at a temperature in the range 20 to 100 C. in the presence of oxygen and re covering a sulfur-containing, benzene-insoluble rubber material.

4; The process of claim 3 in which the poly't'iutadiene.

a' synthetic rubberycopoly'mer of butadiene and styrene a small modifying amount of monovinylcyclohexanethiol. 7. A process for preparingua synthetic rubber which comprises polymerizing a-rubber recipe selected from the group consisting of recipes yielding a polybutadiene and a butadiene-styrene rubber containing a small modifying amount of monovinylcyclohexanethiol.

8. A process for the preparation of a chemically modified synthetic rubber-like polymer selected from the group consisting of polybutadiene and butadiene-styrene c0- polymer-w-hich comprises incorporating into the polymer during the preparation of said polymer a small modifying amount of vinylcyclohexanethiol.

9. A-proce'ss for preparing a polymer from a recipe selected from the group consisting of recipes yielding a polybutadiene and a buta'diene-styrene rubber which comprises incorporating 0.10.6 weight percent based on the final rubber of vinylcyclohexanethiol into said recipe.

10. A process for modifying a polybutadiene which comprises contacting together for an extended time in the presence of oxygen, at polybutadiene and a vinylcyclohexanethiol, theproportion' of the vinylcyclohexanethiol added being sufiicient to saturate double bonds in the polybntad-ieneto an extent touender the" final product insoluble inbenzene to'a"substantial extent.

l1: Theprocess'bfclaim' 3 in which the'p'olybutadiene is" in theform of a benzene solution of 'polybutadiene.

References'Cited in the file of this patent UNITED STATES PATENTS 2,543,867

2,806,8 1? Welch Sept. 17, 1957 Pritchard Mar. 6, 1951' 

1. A SYNTHETIC RUBBER SELECTED FROM THE GROUP CONSISTING OF POLYBUTADIENE AND A BUTADIENE-STYRENE-COPOLYMER RUBBER WHICH IS CHEMICALLY MODIFIED BY THE INCORPORATION THEREIN OF A SMALL MODIFYING AMOUNT OF MONOVINYLCYCLOHEXANETHIOL. 